Technique for extracting alumina from materiel containing calcium aluminate

The invention provides a new technology for extracting aluminium oxide from the material containing carbon aluminate. The carbon aluminate is dissolved out the material by weak sodium carbonate solution to be made into carbon aluminate solution that density is less than 100 g/f, gas CO2 is send into the carbon aluminate solution to do decomposition to generate high-silicon aluminium hydroxide and carbon decomposition mother solution which circulately dissolving out carbon aluminate, the high-silicon aluminium hydroxide is processed by low-temp. dissolving, seed-decomposed decomposing and burning to produce quality sand-type aluminium oxide.